Add the ability to specify a reserved space size when making filesystems.

If you specify a negative length when making a filesystem, then the
filesystem size is the size of the partiton (or image file) minus
the absolute value of the negative length specified.

Change-Id: I53e3b6de2ea692f4678682c3f49ff36429d9ad31

diff --git a/ext4_utils/ext4_utils.c b/ext4_utils/ext4_utils.c
index 1804e4b..bdf2a74 100644 (file)
--- a/ext4_utils/ext4_utils.c
+++ b/ext4_utils/ext4_utils.c
@@ -103,7 +103,7 @@ int count_sparse_chunks()
 
        for_each_data_block(count_data_block, count_file_block, &count_chunks);
 
-       if (count_chunks.cur_ptr != info.len)
+       if (count_chunks.cur_ptr != (u64) info.len)
                count_chunks.chunks++;
 
        return count_chunks.chunks;
@@ -442,17 +442,29 @@ u64 get_file_size(const char *filename)
 {
        struct stat buf;
        int ret;
+       u64 reserve_len = 0;
+       s64 computed_size;
 
        ret = stat(filename, &buf);
        if (ret)
                return 0;
 
+       if (info.len < 0)
+               reserve_len = -info.len;
+
        if (S_ISREG(buf.st_mode))
-               return buf.st_size;
+               computed_size = buf.st_size - reserve_len;
        else if (S_ISBLK(buf.st_mode))
-               return get_block_device_size(filename);
+               computed_size = get_block_device_size(filename) - reserve_len;
        else
-               return 0;
+               computed_size = 0;
+
+       if (computed_size < 0) {
+               warn("Computed filesystem size less than 0");
+               computed_size = 0;
+       }
+
+       return computed_size;
 }
 
 u64 parse_num(const char *arg)

diff --git a/ext4_utils/ext4_utils.h b/ext4_utils/ext4_utils.h
index 8f3a64d..b770294 100644 (file)
--- a/ext4_utils/ext4_utils.h
+++ b/ext4_utils/ext4_utils.h
@@ -76,6 +76,7 @@ extern int force;
 #define __u8 u8
 
 typedef unsigned long long u64;
+typedef signed long long s64;
 typedef unsigned int u32;
 typedef unsigned short int u16;
 typedef unsigned char u8;
@@ -94,7 +95,9 @@ struct ext2_group_desc {
 };
 
 struct fs_info {
-       u64 len;
+       s64 len;        /* If set to 0, ask the block device for the size,
+                        * if less than 0, reserve that much space at the
+                        * end of the partition, else use the size given. */
        u32 block_size;
        u32 blocks_per_group;
        u32 inodes_per_group;

diff --git a/ext4_utils/make_ext4fs.c b/ext4_utils/make_ext4fs.c
index 3fee133..a366a37 100644 (file)
--- a/ext4_utils/make_ext4fs.c
+++ b/ext4_utils/make_ext4fs.c
@@ -249,7 +249,7 @@ int make_ext4fs(const char *filename, const char *directory,
         u32 root_inode_num;
         u16 root_mode;
 
-       if (info.len == 0)
+       if (info.len <= 0)
                info.len = get_file_size(filename);
 
        if (info.len <= 0) {

diff --git a/ext4_utils/output_file.c b/ext4_utils/output_file.c
index 66550d5..c1997b6 100644 (file)
--- a/ext4_utils/output_file.c
+++ b/ext4_utils/output_file.c
@@ -333,7 +333,7 @@ void pad_output_file(struct output_file *out, u64 len)
 {
        int ret;
 
-       if (len > info.len) {
+       if (len > (u64) info.len) {
                error("attempted to pad file %llu bytes past end of filesystem",
                                len - info.len);
                return;
@@ -370,7 +370,7 @@ void write_data_block(struct output_file *out, u64 off, u8 *data, int len)
 {
        int ret;
        
-       if (off + len > info.len) {
+       if (off + len > (u64) info.len) {
                error("attempted to write block %llu past end of filesystem",
                                off + len - info.len);
                return;
@@ -397,7 +397,7 @@ void write_data_file(struct output_file *out, u64 off, const char *file,
        off64_t aligned_offset;
        int aligned_diff;
 
-       if (off + len >= info.len) {
+       if (off + len >= (u64) info.len) {
                error("attempted to write block %llu past end of filesystem",
                                off + len - info.len);
                return;